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A.  I.  34.  r  Issued  July  16. 19ia 

United  States  Department  of  Agriculture, 

BUREAU  OF  ANIMAL  INDUSTRY. 

JOHN  R.  MOHLER,  Chief  of  Bureau. 


NOTES   ON  LARKSPUR  ERADICATION   ON    STOCK 

RANGES. 

By  C.  Dwight  Marsh  and  A.  B.  Clawson,  of  the  Pathological  Division. 

The  losses  of  cattle  from  larkspur  upon  the  range  continue  to  be 
very  large,  but  are  being  reduced  gradually  as  stockmen  use  more 
and  more  the  measures  which  have  been  found  effective  and  are 
given  in  detail  in  the  publications  of  the  United  States  Department 
of  Agriculture. 

There  are  three  ways  by  which  the  losses  may  be  reduced:  (1)  By 
the  use  of  the  medicinal  remedy;  (2)  by  herding  the  animals  away 
from  the  plants  during  the  time  when  they  are  most  poisonous; 
(3)  by  destroying  the  plant. 

As  indicated  in  previous  publications,  the  main  reliance  must  be 
upon  the  second  and  third  methods,  inasmuch  as  many  cases  of 
poisoning  occur  when  the  remedy  can  not  be  applied  because  the 
stockman  is  not  on  hand  at  the  right  time. 

In  the  attempts  to  eradicate  the  plant  many  areas  of  larkspur 
have  been  grubbed  out.  That  this  work  is  an  economic  success  there 
is  no  question.1  Where  complete  eradication  is  an  impossibility,  it 
happens  frequently  that  enough  of  the  plant  may  be  destroyed  to 
reduce  the  losses,  if  not  eliminate  them  completely;  for  it  must  be 
remembered  that  a  considerable  quantity  of  the  plant  must  be  eaten, 
and  in  a  short  time,  to  produce  serious  illness.  Even  if  the  work 
had  to  be  repeated  frequently  it  would  still  be  profitable,  for  the 
value  of  a  single  steer  will  pay  for  a  large  amount  of  work,  and  in 
many  restricted  areas  the  annual  losses  of  cattle  are  quite  large. 

It  has  appeared,  however,  that  in  some  localities  the  work  of  dig- 
ging up  the  larkspur  has  not  been  so  successful  in  eliminating  the  plant 
as  could  be  desired,  and  an  examination  of  the  areas  where  digging 
has  been  tried  has  led  to  the  belief  that  the  cutting  of  the  roots  may 
have  left  some  buds.  In  Bulletin  365,  United  States  Department  of 
Agriculture,  it  is  stated  that  tall  larkspur  can  be  killed  by  cutting 
the  root  2  or  3  inches  from  the  surface.  This  $tatement,  however, 
was  based  on  preliminary  observations. 

Under  the  circumstances  it  seemed  desirable  to  make  some  definite 
experiments  to  determine  more  exactly  what  was  necessary  to 
insure  that  the  plants  were  actually  killed.     The  results  of  these 

1  See  Fanners'  Bulletin  826,  "  Eradicating  Tall  Larkspur  on  Cattle  Ranges  in  the  National  Forests  " 
64345°— 18 


experiments  and  observations,  while  not  as  complete  as  may  be 
desired,  inasmuch  as  only  a  few  species  have  been  under  observation, 
nevertheless  are  sufficiently  definite  to  be  of  decidedly  practical 
importance,  and  it  is  thought  that  they  should  be  published  in 
order  to  assist  those  who  are  attempting  to  grub  out  the  plants. 

EXPERIMENTS  IN  CUTTING  ROOTS. 

The  roots  of  the  tall  larkspur  are  tough  and  fibrous,  of  varying 
lengths  up  to  a  foot  or  more,  and  live  for  an  undetermined  number 
of  years,  the  older  part  of  the  root  dying  off.  The  annual  shoots 
originate  on  the  upper  part  of  the  root  from  buds,  some  of  which 
are  beneath  the  surface  of  the  ground. 

One  question  for  solution  was  whether,  when  the  upper  part  of 
the  root  was  cut  off  below  existing  buds,  adventitious  buds  might 
not  be  formed  on  the  remaining  portion  of  the  root,  so  that  there 
would  be  danger  of  further  growth  if  any  part  of  the  root  remained. 

If  it  were  found  that  adventitious  buds  were  not  liable  to  be  formed, 
it  was  necessary  to  determine  how  far  beneath  the  surface  of  the 
ground  it  was  necessary  to  cut  the  root  in  order  to  stop  further 
growth. 

To  settle  these  questions,  definite  experimental  evidence  was 
sought,  with  the  following  results: 

DELPHINIUM  BARBEYI. 

On  an  area  in  the  Fishlake  National  Forest,  Utah,  on  August  13, 
1916,  28  plants  of  Delphinium  barbeyi  were  selected  and  cut  off  at 
various  depths.  These  roots  were  marked  and  examined  again  on 
August  22,  1917.     The  following  table  gives  the  results: 

Results  of  experiments  in  cutting  roots  of  Delphinium  barbeyi. 


Plant 

No. 

Distance  of  cut  below  surface  of 
ground. 

Distance  of  cut  below  buds. 

Result. 

1 

15  cm.  (6  in.) 

Just  below  the  buds 

Root  dead. 

2 

do 

1  living  shoot. 

3 

10  cm.  (4  in.) 

Junction  of  stems  and  rool  s .  . . 
10  cm.  (4  in.) 

2  shoots:  5  buds. 

4 

5 

12  cm.  (5  in.) 

Do. 

6 

12  cm.  (5  in.) 

9  cm.  (3i  in.) 

Do. 

7 

Just  below  the  buds 

1  shoot. 

8 

do 

5  shoots. 

9 

12  cm.  (5  in.) 

No  shoots;  living  tissue  in  roots 

10 

Do. 

U 

4  cm.  (1\  in.) 

Roots  disappeared. 

12 

Do. 

13 

6  cm.  (2  in.) 

Do. 

14 

Just  below  the  buds 

1  shoot. 

15 

10.5  cm.  (4.2  in.)  .. 

No  shoots;  living  tissue  in  roots. 
Do. 

16 

17 

(i  cm.  (2.3  in.) 

1  o. 

is 

10  5  cm    C4  2  in.) 

R  >otS  disappeared. 

<  shoots. 

19 

do 

20 

10.5  cm.  (4.2  in.) 

No  shoots:  living  tissue  in  roots- 

21 

5  cm.  (2  in.) 

8  cm.  (3  in.)       

Just  below  the  buds 

l  o. 

22 

3  cm.  (1  in.) 

Roots  disappeared. 

N  o  shool  s;  living  tissue  in  roots. 

23 

LO  5  cm.  (4.2  in.)  .. 

24 

J  ust  below  the  buds 

3  shoots. 

25 

10.5  cm.  (4.2  in.) 

1  cm.  (2.3  in.) 

N  o  shoots ;  liv ing  tissue  in  roots. 

26 

27 

2.5  cm.  (1  in.) 

1  shoot. 

28 

16  cm.  (6.4  in.) 

N  o  shoots;  living  tissue  in  roots. 



Twelve  of  these  plants  were  cut  off  just  below  the  buds.  Of  these 
12,  4  had  no  shoots.  Of  the  4,  in  2  cases  the  roots  had  disappeared, 
in  1  the  root  was  dead,  and  in  the  remaining  1,  although  there  were 
no  shoots  there  was  still  living  tissue  in  the  root. 

One  plant  was  cut  off  at  the  junction  of  the  stems  with  the  roots 
without  regard  to  buds,  and  in  this  case  there  were  2  shoots  and  5 
buds. 

The  other  15  plants  were  cut  off  at  distances  from  the  buds  vary- 
ing from  2  centimeters  (f  inch)  to  15  centimeters  (6  inches).  Of 
these  there  was  growth  from  only  one,  which  was  cut  at  4  centimeters 
(!■§  inches). 

The  general  inference  from  these  experiments  is  that  a  cut  below 
the  buds  will  stop  further  growth.  The  fact  that  growth  appeared 
in  7  plants  cut  just  below  the  buds  is  probably  explained  by  sup- 
posing that  buds  were  overlooked  rather  than  that  the  growth  was 
from  adventitious  buds.  If  adventitious  buds  grow  from  the  roots 
it  seems  probable  that  they  would  have  been  found  on  some  of  the 
plants  which  were  cut  at  from  2  to  16  centimeters  (f  to  6.4  inches) 
from  the  1916  buds. 

It  seems  clear,  too,  that  if,  to  avoid  the  result  of  defective  observa- 
tion, the  cut  is  made  from  4  to  5  centimeters  (1-|  to  2  inches)  below 
observed  buds,  further  growth  will  certainly  be  prevented. 

These  plants  were  examined  July  1,  1917.  At  that  time  Nos.  2,  7, 
14,  19,  20,  and  27  had  no  shoots,  although  on  August  22  all  had 
shoots.  This  would  indicate  that  some  of  the  shoots  start  rather  late 
in  the  season,  and  that  the  most  effective  time  for  grubbing  plants  is 
at  the  period  of  blossoming,  when  all  the  shoots  of  the  year  have 
appeared. 

It  should  be  noted  that  13  of  the  experimental  plants  still  had 
living  tissues  in  their  roots,  although  no  shoots  had  sprung  from 
them.  These  plants  are  still  under  observation,  but  it  is  not  deemed 
probable  that  there  will  be  any  further  growth. 

In  23  cases  notes  were  kept  in  regard  to  the  depth  of  the  cut  below 
the  surface  of  the  ground.  These  notes  have  a  considerable  possible 
margin  of  error,  inasmuch  as  it  is  difficult  to  measure  the  distance 
exactly.  Of  the  7  plants  cut  at  8  centimeters  (3  inches)  or  less,  4 
produced  shoots.  Of  4  cut  at  10  centimeters  (4  inches),  3  produced 
shoots.  From  12  cut  at  10.5  centimeters  (4.2  inches)  or  more,  there 
was  no  growth.  The  inference  for  practical  purposes  is  that  the  cut 
should  be  12  centimeters  (5  inches)  or  more  below  the  surface. 

Air.  W.  W.  Eggleston,  representing  the  Bureau  of  Plant  Industry, 
who  cooperated  in  this  work,  dug  up  and  examined  15  plants  of  this 
same  species  (Delphinium  barbeyi)  on  the  Gunnison  National  Forest 
in  Colorado,  and  found  that  the  buds  were  from  3  to  5  inches  below 
the  surface. 


The  general  inference  from  the  observations  on  D.  barbeyi  in  these 
two  localities  is  that  laborers  who  dig  up  this  species  of  larkspur 
should  be  instructed  to  cut  the  roots  at  least  6  to  8  inches  below  the 
surface  to  be  sure  of  effective  results. 

DELPHINIUM  CUCULLATUM. 

Delphinium  cucullatum  is  the  common  species  of  tall  larkspur  in 
Montana  and  is  found  in  some  of  the  adjoining  States. 

On  September  7,  1917,  27  specimens  of  this  plant  were  collected  by 
W.  W.  Eggleston  in  Cottonwood  Canyon  near  Fairview,  Utah.  These 
were  measured  with  reference  to  the  depths  of  the  buds  below  the 
surface,  with  the  following  results: 

Results  of  examination  of  Delphinium  cucullatum  to  determine  depth  of  buds  below  surface. 


Depth  of  buds  below  surface. 


4cm.  (1.5  in.) 

5  cm.  (2  in.) 

6.35  cm.  (2.5  in.).. 

3  cm.  (3  in.) 

10.5  cm.  (4  in.).... 
11.43  cm.  (4.5  in.). 

12  cm.  (5  in.) 

13.99  cm.  (5.5  in.). 
15  cm.  (6  in.) 


Number 
of  plants. 


It  is  seen  that  the  greatest  distance  from  the  surface  at  which 
buds  were  found  was  6  inches,  and  that  in  23  of  the  27  plants  no 
buds  were  found  below  4  J  inches.  It  is  evident  that  to  be  sure  of 
killing  D.  cucullatum  by  grubbing,  the  cut  should  be  8  inches  below 
the  surface  of  the  ground. 

DELPHINIUM  GERANIIFOLIUM 

A  cursory  examination  was  made  of  a  few  plants  of  Delphinium 
geraniifolium  near  Flagstaff,  Ariz.  It  was  found  that  in  order  to 
be  reasonably  certain  of  cutting  below  the  buds  this  species  should 
be  cut  at  least  6  inches  below  the  surface. 

SOME  SPECIES  MORE  EASILY  DESTROYED. 

It  is  known  that  some  species  of  high  larkspurs  have  a  much  more 
shallow  root  system  than  the  three  which  have  been  discussed. 
This  is  true  of  some  of  the  high  larkspurs  occurring  in  Idaho  in  which 
the  root  is  so  short  that  in  many  cases  it  is  not  difficult  to  pull  it  up, 
especially  when  the  ground  is  wet.  Where  this  can  be  done  it  is 
certain  to  destroy  the  plant  and  its  eradication  can  therefore  be 
accomplished  with  less  labor  than  is  necessary  where  all  the  plants 
have  to  be  grubbed  out. 


SUMMARY. 

1.  Attempted  eradication  of  larkspur  from  stock  ranges  in  the 
West  in  some  cases  has  not  been  as  satisfactory  in  eradicating  the 
plants  as  it  might  have  been,  because  the  roots  were  not  cut  at  the 
depth  necessary  to  stop  further  growth. 

2.  Experimental  cutting  of  Delphinium  barbeyi  followed  by  obser- 
vation of  the  effect  a  year  later  shows  that  to  insure  results  the  roots 
should  be  cut  at  least  from  6  to  8  inches  below  the  surface. 

3.  Observations  upon  two  other  species,  D.  cucullatum  and  D. 
geraniifolium,  show  that  in  them  also  the  cutting  should  be  at  least 
from  6  to  8  inches  below  the  surface. 

4.  Certain  of  the  high  larkspurs  have  shallow  roots,  so  that  many 
of  the  plants  can  be  pulled  up. 

5.  In  giving  directions  to  laborers  who  are  engaged  to  grub  out 
tall  larkspur  it  is  best,  in  the  case  of  all  larkspurs,  to  require  from 
6  to  8  inches  of  the  root  to  be  dug  up. 

It  should  be  noted  in  this  connection  that  the  larkspur  which  is 
dug  up  should  not  be  left  in  piles  where  cattle  can  get  at  it,  for  the 
dried  larkspur  is  toxic  and  sometimes  cattle  show  an  especial  fond- 
ness for  it.  There  have  been  cases  of  rather  heavy  losses  under 
such  circumstances. 

6.  The  best  time  to  dig  the  larkspur  is  at  about  the  period  of 
blossoming,  for  earlier  all  the  shoots  of  the  year  will  not  have  devel- 
oped. 

Of  course  in  subsequent  years  seedlings  will  have  to  be  dealt  with, 
for  the  plants  grow  from  both  roots  and  seeds. 


PUBLICATIONS  OF   THE    UNITED   STATES   DEPARTMENT   OF   AGRICUL- 
TURE RELATING  TO  POISONOUS  PLANTS. 

AVAILABLE  FOR  FREE  DISTRIBUTION  BY  THE  DEPARTMENT. 

Zygadenus,  or  Death  Camas.     (Department  Bulletin  125.) 

Lupines  or  Poisonous  Plants.     (Department  Bulletin  405.) 

Prevention  of  Losses  of  Live  Stock  from  Plant  Poisoning.     (Farmers'  Bulletin  720.) 

Eradicating  Tall  Larkspur  on  Cattle  Ranges  in  the  National  Forests.  (Farmers' 
Bulletin  826.) 

Larkspur,  or  "Poison  Weed."     (Farmers'  Bulletin  988.) 

The  Cause  of  the  "Spewing  Sickness''  of  Sheep.     (Leaflet  A.  9.) 

Cicuta  (Water  Hemlock)  as  a  Poisonous  Plant.     (Leaflet  A.  15.) 

White  Snakeroot  or  Rich  weed  (Eupatorium  urticsefolium)  as  a  Stock-Poisoning  Plant. 
(Leaflet  A.  I.  26.) 

Eupatorium  urticaefolium  as  a  Poisonous  Plant.  (Reprint  from  the  Journal  of  Agri- 
cultural Research,  A  33.) 

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